"Of the automobiles currently on the road, a 400 pound car is twice as safe as a 200 pound car."

990–1980 kg

A car is made out of many different kinds of materials, such
as metals, plastics, and rubber. Cars greatly vary in size, and
therefore in mass. A car's mass may vary in the range of 990 to
2000 kg. However, a typical car may require more than 770 kilograms
of steel, 180 kilograms of iron, 110 kilograms of plastics,
80 kilograms of aluminum, and 60 kilograms of rubber,
as well as, less significant amounts of different materials. The
total mass of an average car may be about 1500 kilograms.

One of the most important things about the mass of a car, is
the fact that the heavier it is, the safer it for the occupants, and vice versa.
In fact, the mass and safety of a car are said to be directly
proportional, so a 2000 kg car is twice as safe as a 1000 kg
car. In special studies, it was found out that in most cases,
the numbers of crashes between cars are directly proportional
to the difference in masses of the two cars. In case of two-car
crashes, the effect flows directly from Newton's laws of motion,
which require that when two objects collide, the speed change
each undergoes is in inverse proportion to its mass. It is this
speed change that generates the forces that lead to death and
injury.